The electrophoretic display (EPD) is a non-emissive device based on the electrophoresis phenomenon of charged pigment particles suspended in a solvent. The display usually comprises two plates with electrodes placed opposing each other, separated by spacers. One of the electrodes is usually transparent. A suspension composed of a colored solvent and charged pigment particles is enclosed between the two plates. When a voltage difference is imposed between the two electrodes, the pigment particles migrate to one side or the other, according to the polarity of the voltage difference. As a result, either the color of the pigment particles or the color of the solvent is seen from the viewing side. Alternatively, the suspension may comprise a clear solvent and two types of colored particles which migrate to opposite sides of the device when a voltage is applied. Further alternatively, the suspension may comprise a dyed solvent and two types of colored particles which alternate to different sides of the device. In addition, in-plane switching structures have been shown where the particles may migrate in a planar direction to produce different color options.
There are several different types of EPDs, such as the conventional type EPD, the microcapsule-based EPD or the EPD with electrophoretic cells that are formed from parallel line reservoirs. EPDs comprising closed cells formed from microcups filled with an electrophoretic fluid and sealed with a polymeric sealing layer is disclosed in U.S. Pat. No. 6,930,818, the entire contents of which are hereby incorporated by reference as if fully set forth herein.
Currently available driving methods for electrophoretic displays have certain disadvantages. For example, they are incapable of providing fast response for input actuation. As a result, the methods often render the electrophoretic displays not useful for applications which require instant feedback, such as input-enabled devices. In addition, black and white flashes which are often used between images may be considered annoying by the user.